The present invention relates to a plasma etching method of plasma-etching a magnetic film which is used in a magnetoresistive random access memory or the like.
Along with an increase in an amount of information in recent years, promotion of low power consumption has been required for electronic apparatuses. A semiconductor memory used in the electronic apparatuses has also been required to be a nonvolatile memory which is operated as a high speed and which continues to hold information even when no electric power is supplied thereto from a power source. From these requests, the adaption of a Magnetoresistive Random Access Memory (MRAM) (hereinafter referred to as “an MRAM”) is expected as the non-volatile memory which is operated at the low power consumption and at the high speed.
In the manufacture of the MRAM, there is required a technique for micro-fabricating a magnetic film which contains therein at least one of ferromagnetic metals, such as iron (Fe), cobalt (Co), and nickel (Ni), and which is formed on a substrate by a dry etching process using a mask manufactured through a lithography process. The demand for the technique for micro-fabricating the magnetic film by the dry etching process has been increased in the processing as well, for a magnetic head, using the magnetic material.
The methods for etching the magnetic films by the dry etching process include a method using an ion beam etching process, and a method using a plasma etching process. In particular, the plasma etching is widely used in the manufacture of the semiconductor devices, and is excellent in mass productivity because it enables a large-diameter substrate to be uniformly processed. However, when the magnetic film is micro-fabricated by the plasma etching process using halogen system gas such as fluorine (F), chlorine (C) or bromine (Br) which has been heretofore used, the micro-fabrication is difficult to carry out because a vapor pressure of a halogen compound of the magnetic film is low. In addition, it is necessary to specially carry out an anticorrosion treatment because the corrosion is caused when the halogen compound deposited on the magnetic film touches the moisture in the atmosphere.
As far as a method of solving the problems described above, JP-A-2004-356179 discloses a dry etching method of processing a magnetic material while dissociation of a carbon monoxide in plasma is suppressed. This method utilizes that metal carbonyl exhibiting a high vapor pressure is created, and thus is suitable for processing for a magnetic film because corrosion or the like is not caused.